Background Previous studies show that aluminum exposure could increase the expression of miRNA-134-3p, which is involved in the mechanism of aluminum induced learning and memory impairment. However, it has not been investigated whether the expression level of miRNA-134-3p in the peripheral blood of occupational aluminum exposed workers is related to the blood aluminum concentration yet.

Objective To evaluate a potential correlation between aluminum concentration in peripheral blood and miR-134-3p expression in occupational aluminum exposed workers.

Methods A total of 184 male aluminum workers in the electrolytic aluminum workshop, aluminum oxide workshop, and thermal power workshop of an aluminum plant in Shanxi were selected by cluster sampling. They were divided into four groups (Q₁-Q₄) according to the quartiles of blood aluminum concentration, with 46 workers in each group. The basic information of workers was collected by questionnaire survey, and the cognitive function of workers was evaluated by Montreal Cognitive Assessment (MoCA). The plasma of workers was collected, and the relative expression level of miR-134-3p in plasma was detected by real-time quantitative polymerase chain reaction (RT-PCR). The plasma aluminum concentration was detected by inductively coupled plasma mass spectrometry (ICP-MS). The associations among workers' peripheral blood aluminum concentration, plasma miR-134-3p expression level, and total MoCA score were evaluated by generalized linear models.

Results The workers' medians (P₂₅, P₇₅) of blood aluminum concentration, plasma relative expression level of miR-134-3p, and MoCA score were 39.31 (25.30, 57.41) μg·L^-1, 2.93 (2.29, 3.74), and 22.0 (20.0, 26.0), respectively. The results of the generalized linear model showed that after adjusting for age, body mass index, smoking, and alcohol consumption, compared with the Q₁ group, blood aluminum in the Q₂, Q₃, or Q₄ group had an impact on related plasma miR-134-3p expression level and total MoCA score (P<0.05). With increasing blood aluminum concentration, the expression level of miR-134-3p in workers' plasma gradually increased, showing a positive correlation (b>0, P_trend<0.001), while the total score of MoCA gradually decreased, showing a negative correlation (b<0, P_trend<0.001). As the expression level of miR-134-3p in plasma increased, the total score of MoCA gradually decreased, showing a negative correlation (b<0, P_trend<0.001). There was a linear relationship between peripheral blood aluminum concentration and plasma relative expression level of miR-134-3p of the workers in the middle school and below group and the high school group (P_trend<0.05), b (95%CI)=1.796 (1.248, 2.344) and 1.192 (0.874, 1.510), and no correlation was found in the workers in the college and above group (P_trend>0.05).

Conclusion Occupational aluminum exposure can lead to an increase in the expression level of miR-134-3p in plasma of workers, which may be related to a decrease in cognitive function of workers.